The treatment of malignant gliomas remains one of the greatest challenges facing adult and pediatric oncologists today. At the most severe end of the spectrum is glioblastoma multiforme (GBM)—among the most malignant of cancers, with a median survival of less than 12 months and an inherent resistance to both chemo- and radio-therapeutics (DeAngelis, N. Engl. J. Med. 344, 114-123, 2001). While initial treatment of GBM with surgery, radiotherapy and chemotherapy often produces some palliation of symptoms, these tumors almost universally recur with an unrelenting progression to death. Despite great advances in our understanding of the molecular causes of GBM (Kitange et al., Curr. Opin. Oncol. 15, 187-203, 2003), there has been very little improvement in outcomes for patients with GBM.